Tasmanian Devils Fight Back Against Contagious Cancer

Cancers are a large group of diseases that have abnormal cell growth that have the potential to invade and spread around the body. Essentially, cancers are our own cells that have mutated that do not die when they are supposed to and instead keep proliferating. Therefore, cancers are not normally contagious. However, a recently emerged transmissible cancer in Tasmanian devils has swept through the population with an approximate 100% mortality rate. Devil facial tumor disease is a single tumor that is passed between hosts, usually through a bite. Over the past 20 years, the population of Tasmanian devils has been reduced by up to 80% by this contagious cancer. Only two other contagious cancers are known to exist, one in dogs and the other in clams. There have also been isolated cases of contagious cancer in humans, although, only through human error.

Researchers have identified signs that the animals are rapidly evolving to fight back against this contagious cancer. The study used the latest DNA sequencing methods to look for changes in the genome and identify genetic variants that could convey resistance. Two stretches of DNA were identified as sections that had given raise to genetic variations and seven genes look like good anti-cancer candidates. All genes identified are linked to the activity of the immune system. It is remarkable that the genetic variations evolved within six generations of the species. This result suggests that the species may now survive the contagious cancer and save themselves from extinction. Can we figure out how contagious cancers evolved in the first place? Will this resistance lead to susceptibility to other diseases? Further work is needed to characterize the genes identified and to see if this knowledge can help fight cancer in humans.